SimpleShader.metal

struct VertexIn {
    simd_float4 position;
    simd_float4 color;
};

struct VertexOut {
    simd_float4 position [[position]];
    simd_float4 color;
};

vertex VertexOut vertex_main(uint vertexID [[vertex_id]],
                             constant VertexIn *vertices [[buffer(0)]]) {
    VertexIn in = vertices[vertexID];
    VertexOut out;
    
    out.position = in.position;
    out.color = in.color;    
    return out;
}

fragment float4 fragment_main(VertexOut in [[stage_in]]) {
    return in.color;
}